Filtering apparatus



Feb. 9, 1926.

FIG.1

'F. B. LEOPOLD FILTERING APPARATUS Filed May 12, 1924 2 Sheets-Sheet l Feb. 9 1926,;

' F. B. LEOPOLD FILTERING APPARATUS Filed May l2, 1924 2 Sheets-Sheet 2 lll Patented Feb'. 9, 1926.

UNITED STATES FREDERICK B. LEOPOLD, F BITTSBURGH, PENNSYLVANIA..

FILTERNG APPARATUS.

./ippneaamfi filed May 12, 1924. serial no. 712,625.

To all whom it may. concern.'

Be it known that I, FREDERICK B. LnoroLD, a citizen of the United States, and resident of Pittsburgh, in the countyk of Allegheny and State of Pennsylvania, have invented a new and useful improvement in Filtering Apparatus; and l do hereby declare the following to be a full, clear, and exact. description thereof.

My invention relates to filtering apparatus and particularly to means for effecting a uniform distribution of flow through a filter bed.

l-leretofore difficulty has been experienced in effecting proper distribution of the flow of wash water through a filter' bed of sand and gravel7 the usual practice being to re" verse the flow through the filter at frequent intervals to loosen and carry off the sludge deposited in the filter bed. ln backwashing,

the tendency is for the flow to concentrate atA points in the filter bed where the resistance thereto is relatively weak owing to the variation in density or tenacity7 of the filter bed by reason of certain portions thereof becoming more clogged with sediment than other portions. Consequently the water breaks through at weaker points and dis places the smaller particles of gravel ad-` acent thereto and builds it up into mounds that extend to the surface of Vthe sand. A relatively free passage for raw water there after supplied to the filter is thus afforded, and a considerable portion thereof will pass through the filter bed without depositing the sediment contained therein.

Various attempts have been iliade to insure uniform flow of wash water through a filter. as by placing shields or deflectors above the bottom of the filter tank or by providing branch lines through which the water is conveyed to separated points at the bottom of the filter bed. but in all of these arrangements the actual distribution of the water through the filter bed is controlled by the gravel in the bottom of the bed, the water being directed through the openings between the particles of gravel in a rather uncertain manner. lt will be apparent that when a line of weak resistance is established in the gravel bed subsequent washing will increase the rupture at such line and the filter bed will become increasingly ineffective at each repeatedwashing, and this abnormal condition may be present for a considerable period of time before it is finally discovered and corrected.

One object of my invention is to provide a system wherein a uniform distribution of flow through the filter is insured.

Another object of my invention is to simplify and improve generally the construction and operation of filter beds and the distribution of liquid flow thereto.

One form which my invention may take is shown in the accompanying drawing wherein Fig. l is a sectional view of a por` tion of filter tank to which my invention has been applied; Fig. 2 is a sectional plan view of the device of Fig. l taken at three vertically placed points, and Fig. 3 is a sectional view taken on the line 3 3 of Fig. 2.

.ly apparatus is shown as applied to a concrete tank 4, only the lower' portion of which is shown in Fig. l. Within this is found the usual filter bed 5 composcdof sand and gravel. f

Disposed longitudinally of the tank l is a collecting flume or conduit 6 through which filtered water flows when leaving the .ta-nk and through which Wash water is drawn in the reverse direction when it is desired to wash the filter bed by back-flow therethrough.

Extending laterally from the collecting flume are a plurality of tributary tlumes or branches 7 formed in a-slab S of concrete or other suitable material. lt. will be noted (Fig. l) that the branches 7 taper towards their ends. so that uniform pressure will be maintained in each throughout its length when liquid is flowing through the passages leading therefrom. The slab 8 is anchored to the tank by bolts 9.

A plurality of pipes l0 are embedded in the slab 8 and afford communication between the passages 7 and chambers located thereabove, which will be hereinafter described. l'ach tributary passage 7 is provided in the present instance, with two rows of pipes l() throughout substantially its entire length.

One or more chambers l1 are disposed above each of the tributary passages 7, these chambers being formed by inverting troughs or recessed blocks l2 over groups of pipes l0. The blocks 12 are formed of conc-rete or other suitable material and are provided with side and end walls 13. The

blocks are each provided with a plurality of tapered openings 14 through which water may pass from the filter bed ,to the chambers ll or from such chambers to the filter bed, the tapering construet'on serving to reduce the tendency of the openings lato become clogged by material from the filter bed. The combined area of the openings le attheir upper ends is greater. than the sum of the areas of the passages through the pipes 10, and the openings la are preferably uniformly distributed throughout the tops of the blocks l2. The main conduit (S and the lateral conduit 7 `together const?.- tutes what maybe termed the primary distribution system, while the chambers "ll and passages lt form the secondary system. Each section of the .secondaryr system is a unit in itself and has nov direct communica.- tion with the other port'ons of the secondary system, and the combined areas ot the outlets from the chambers ll to the filter bed is so proportioned with respect to the areav of the passages leading to the primary system that the velocitaY ot flow from the primary .system is so reduced that it is insuiicient to disturb the gravel located adj acent to the bottom of the filter bed and the velocity of backiow through the filter bed will therefore not be so great at any one point as to cause a break in the filter bed.

Itwill be understood that materials other than concrete may be employed for constructing the various conduitsA and chambers, and that various changes in detail and general 'arrangement may be made without departing from the spfrit and scope of the invention as defined in the accompanying claims:

IYhat I claim is:

l. The combination with a filter bed, of

a water distribution .system therefor comprising a. main 'conduit beneath said bed,

lateral conduits leading from said main conduit, and a. chamber disposed above each of said lateral conduits and having openings communicating With the bottom of the lilter bed, the lateral conduits being of decreasing area from said main conduit and provided With a plurality of passages throughout their lengths for effecting ycommunication between .said lateral conduits and their associated chambers, the combined areas of the said openings being greater than the area of said passages.

2. The combination with a iilter bcd,of a distribution system therefor comprising a main channel, lateral 'channels leading from said main channel, 'chambers disposed above said lateral passages and said main channel, tubes leading from said passages to the said ychambers and having their upper ends bent downwardly, and means' providing communication between said chambers and the filter bed.

3. The combnation with a filter bed, of a distributionv system therefor comprising` a main channel, lateral channels leading from said main channel, Ichambers disposed above said lateral passages and said main passage, means aifording \,comnnmication between said passages and the said chambers, and

means irovid'no' communication between 

